The present invention relates to an air filtration system for a cooking stove and, more particularly, to an air filtration system which filters exhaust air from a stove and returns the filtered exhaust air back into the room.
Exhaust air from cooking stoves consists of warm air containing grease, particulate matter and odors. It is desirable to remove this exhaust air from the immediate vicinity of the cooking stove so that the air supply does not become stale or rancid. For this purpose, cooking stoves are commonly provided with venting arrangements for exhausting air from the vicinity of the stove to atmosphere outside the building. Generally, a fan is used to draw air to be exhausted from the area in which the stove is used and expel the air to the exterior of the building. Filters for removing grease from the air are commonly included within the air filtration system.
Cooking stoves generally are divisible into two distinct classes of stoves, namely residential and commercial. Residential cooking stoves are used within a residential dwelling to prepare only a few meals per day for a small number of people. These residential stoves have a daily use generally in the range of two to four hours. Resultant exhaust air from residential stoves is therefore minimal and occurs for only short periods of time. Commercial cooking stoves, the second class, present different problems in view of the larger sizes, greater hourly use, and the quantity and variety of foods cooked thereby. Daily total use of a commercial stove can average eleven hours per day. The quantity of air exhausted from a commercial stove is therefore considerable and the air is exhausted continuously for extended periods of time.
Cooking stove air filtration systems which expel exhaust air to the exterior of a building present problems of replenishing the air supply within the building. In this respect, while the venting arrangement operates to exhaust air from the vicinity of the stove and thus the room, no provision is made for supplying fresh air to the room in quantities equivalent to the air eliminated. To some extent recirculation of exhaust air has been accomplished with regard to residential cooking stoves. In this respect, exhaust air is drawn through a charcoal filter by a fan and forced back into the room. Because of the relatively infrequent operation of a residential cooking stove, and the small quantity of air to be handled, the charcoal filter need only be capable of handling 100 to 200 cubic feet per minute of exhaust air. As a result, charcoal filters for use in residential stove venting arrangements are feasible. However, systems which may be considered adequate for residential cooking stoves do not provide sufficient filtering and recirculation in the environment of commercial cooking stoves. From the standpoint of size alone, commercial cooking stoves would require a charcoal filter accommodating up to 2000 cubic feet per minute of exhaust air. In addition, the continuous use of cooking stoves in commercial environments for extensive periods of time would cause quick deterioration of charcoal filters.
At present, most commercial stove venting arrangements merely expel the exhaust air into the atmosphere outside the building. As a result of the large quantity of exhaust air from a commercial stove, the air supply within the room could conceivably be depleted to an unacceptable or even unsafe level. While the room in which the commercial stove is being used is not necessarily sealed, the amount of air able to enter the room is extremely limited. Therefore, the large amounts of air drawn from the room by the venting arrangement decreases the air supply in the room to the possible detriment of occupants thereof.
One solution to the problem of decreasing air supply within a commercial kitchen involves introducing fresh, outside air into the room. While this solves the air supply problem, another serious problem is created. In this respect, while the heating or air conditioning system of the building is working to maintain the temperature within the building within a comfortable range for occupants thereof, fresh air from outside the building generally works against the heating or air conditioning systems. In cold weather, for example, the heating system of the building expends energy in the heating of the interior air. Thus, a system which supplies fresh exterior air, interjects cold air into the room, whereby more energy is required to heat the interior of the building. During warm weather, the building air conditioning system expends energy to cool the interior air of the building. Therefore, when warm outside air is supplied to the room, the building air conditioning system must expend additional energy to cool the warm air. In either event, the additional cooling or heating of the supplied external air hampers energy conservation.
As noted above, residential cooking stoves have included air filtration systems which recirculate filtered air back to the room in which the stove is being used. To effectively accomplish this feat, an air filtration system must remove grease, particles and odors from the exhaust air before returning the air to the room. The small size and limited use of stoves in residential applications enables relatively small sized charcoal filters to be used to purify the exhaust air for a period of time. With respect to commercial cooking stoves, however, the large volume of exhaust air and extensive use of the stoves has rendered charcoal filtering of the exhaust air unfeasible due to the size of filter required and the frequency of renewal of the charcoal.